APPLICATION OF HVDC FOR LARGE POWER SYSTEM INTERCONNECTIONS

AC power systems have been developed by applying interconnections, first to the neighboring systems and then to larger complex systems covering parts of or even whole continents to gain technical and economical advantages. With an increasing size of the systems, however, advantages of synchronous AC interconnections diminish because of technical and co-ordination problems and because of high costs for adjustments in the systems. The HVDC technology offers a number of technical and economical advantages for interconnection. Adjustments in the AC systems are not needed. HVDC provides therefore often an overall more economical solution. On long term, however, a hybrid interconnection could be the favorable solution, starting with an HVDC interconnection utilizing its advantages, and later be extended by an additional AC interconnection. In principle, a hybrid AC/DC solution does not have any limitation for the size of the interconnected networks.